The effects of sera from Ra dial painters on the mitogenic responses of normal human lymphocytes.

Sera from former Ra workers were incubated with normal human lymphocytes and the effects produced in stimulation assays with specific mitogens were compared with those observed with incubation using normal human sera. The sera from the Ra workers with high residual body burdens (greater than 0.1 muCi 226Ra) inhibited normal control lymphocytes stimulated with Con A and PHA when compared with control homologous sera. Although a significant suppression was not obtained between high- and low-body-burden groups a trend was indicated. Sera from the highest body-burden worker (0.58 muCi) was inhibitory to all normal lymphocyte populations tested regardless of the mitogen stimulant employed.

Measurement of lymphoblastogenic activity from thorium workers.

Mitogenic stimulation of peripheral blood lymphocyte cultures obtained from 36 thorium workers was studied to determine whether the response of these cells was affected by the individuals' occupational exposure to alpha irradiation. The standard assay involved incubating 2 X 10(5) lymphocytes per test well for 72 hours in the presence of phytohemagglutinin (PHA), concanavalin A (Con A) or pokeweed mitogen (PWM). The results showed that there was a significant decrease in lymphocyte responsiveness of former thorium workers grouped by decade of life when compared with controls of the same decade of life for each mitogen tested with the exceptions of PHA in the 41-50 age group and PWM in the 51-60 age group. We are unable to correlate the decreased response observed with the measured body burdens, external gamma exposure, or thoron exhalation rates in these thorium cases. However, other occupational exposures (i.e., various chemicals used in processing thorium) cannot be eliminated as a possible cause.